Assembly for Turbine Engine

ABSTRACT

An assembly for a turbine engine includes an upstream section and a downstream section, each having an annular row of semi-cylindrical radial recesses and a plurality of flanges positioned between two circumferentially adjacent recesses for holding the two sections together. The recesses form a cylindrical opening when the two sections are assembled. The openings receive pivot sections of variable stator vanes.

This application claims priority under 35 U.S.C. § 119 to Belgium PatentApplication No. 2018/5242, filed 10 Apr. 2018, titled “Assembly forTurbine Engine,” which is incorporated herein by reference for allpurposes.

BACKGROUND 1. Field of the Application

The present application relates to the field of axial turbine engines orturbomachines and more particularly aircraft turbojets. Morespecifically, the present application relates to the design of anassembly for a compressor provided with variable stator vanes.

2. Description of Related Art

Document FR 2565297 A1 describes a gas turbine compressor stator. Thestator vanes are orientable around their axis by means of a connectingrod which is screwed to each vane head. Openings are provided in theferrule to receive the heads of the vanes with a sleeve. A flange thatcloses the openings to enclose the vane heads in the openings. Thesleeve and the heads of the vanes are recessed to cooperate with a boltto maintain radially the vane in the opening.

This design is complex because it involves a large number of parts andthe assembly of such a stator is therefore tedious.

Although great strides have been made in the area of assemblies forcompressors having variable stator vanes, many shortcomings remain.

DESCRIPTION OF THE DRAWINGS

FIG. 1 represents an axial turbomachine according to the presentapplication;

FIG. 2 is a diagram of a turbomachine compressor with an assemblyaccording to the present application;

FIGS. 3 and 4 show respectively the head of a vane and a bottom view ofthe connecting rod;

FIG. 5 illustrates a partial view from above of the arrangement of thetwo sections;

FIGS. 6 and 7 are sectional views of the arrangement of the head of thevane with a welded rod;

FIG. 8 is a section of a vane with an integral rod;

FIG. 9 is a partial isometric view of the arrangement of the twosections; and

FIG. 10 illustrates a partial sectional view of the compressor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present application aims to solve at least one of the problems posedby the prior art. The present application also aims to provide a simplerand more compact design, allowing easier assembly of variable statorvanes. The present application also aims to provide a lightweightsolution, reliable and easy to produce.

The present application relates to an assembly for an aircraft turbineengine, comprising: an annular row of stator vanes each with an airfoiland a head having a pivot section; an actuator for pivoting the vanes,the actuator comprising a ring and connecting rods connecting the ringto each of the vanes; an outer shroud comprising an upstream section anda downstream section, both comprising an internal guiding surface forthe gas flow of the turbine engine, and being axially in contact witheach other, the upstream and the downstream sections comprising, each:an annular row of recesses having a semi-cylindrical shape; and at leastone flange positioned between two circumferentially adjacent recesses ofthe annular row of recesses; the recesses of the upstream section beingarranged radially and circumferentially in correspondence with therecesses of the downstream section so as to form an annular row ofopenings receiving the pivot sections of the vanes, each flange of theat least one flange of the upstream section being fixed to a flange ofthe at least one flange of the downstream section, the head of each ofthe vanes having a radial outer portion on the pivot section, the outerradial portion extending circumferentially and/or axially of a lengthwhich is greater than the diameter of the respective opening; theupstream and downstream sections being provided with an annular row ofradial thickened portions or bosses within which the recesses areformed; the radial thickened portions or bosses being an annular rowbeing interconnected to each other by the flanges.

Thus, the recesses and the flanges of the sections are arranged to allowthe assembling of the sections to one another via the flanges, therecesses of the sections being adapted to be brought together to formcylindrical openings when the two sections are assembled.

According to an embodiment, the downstream section comprises a seat forreceiving the actuator, the seat comprising a cylindrical surface.

According to an embodiment, the cylindrical surface defines a diameterand downstream of the seat, the downstream section does not extendradially of more than said diameter.

According to an embodiment, a flange of the at least one flange isarranged between two circumferentially neighboring recesses of therespective annular row of recesses of the upstream and the downstreamsection.

According to an embodiment, the flanges extend circumferentially fromone recess to the adjacent recess. Thus, the flange extendscircumferentially completely from one recess to the neighboring recessof the two circumferentially neighboring recesses.

According to an embodiment, each of the at least one flange comprisestwo through-holes for receiving screws, each flange having acircumferential length between two neighboring recesses and thethrough-holes being at a distance from one of the two neighboringrecesses that is less than a quarter of the circumferential length ofthe flange.

According to an embodiment, the bosses have an external truncatedsurface.

According to an embodiment, the upstream section comprises a fixationflange at its axial upstream end for assembling the upstream section toa fan casing or a de-icing nozzle. Alternatively or complementarily, thedownstream section comprises a fixation flange at its axial downstreamend for assembling the downstream section to a casing.

According to an embodiment, the assembly further comprises a thirdsection with semi-cylindrical recesses, the third section beingconnected to the downstream section and the recesses of the thirdsection forming openings with additional semi-cylindrical recessesprovided at the downstream end of the downstream section.

According to an embodiment, the connecting rod is integral with thevane, or is welded to the head of the vane. “integral” is intended tomean “made in one piece”, “from one raw bloc of material”.

According to an embodiment, the actuator comprises pads in radialcontact with a cylindrical surface of one of the sections.

According to an embodiment, the flanges radially overlap the ring andare axially distant from it.

The present application also relates to an assembly for an aircraftturbine engine, comprising: an annular row of stator vanes each with anairfoil and a head having a pivot section; an actuator for pivoting thevanes, the actuator comprising a ring and being connected to each vanesthrough connecting rods; an outer shroud comprising an upstream sectionand a downstream section, both comprising an internal guiding surfacefor the gas flow of the turbine engine, and being axially in contactwith each other, the upstream and the downstream sections comprising,each: an annular row of recesses having a semi-cylindrical shape; and atleast one flange positioned between two circumferentially adjacentrecesses of the annular row of recesses; the recesses of the upstreamsection being arranged radially and circumferentially in correspondencewith the recesses of the downstream section so as to form an annular rowof openings receiving the pivot sections of the vanes, each flange ofthe at least one flange of the upstream section being fixed to a flangeof the at least one flange of the downstream section, the head of eachof the vanes having a radial outer portion on the pivot section, theouter radial portion extending circumferentially and/or axially of alength which is greater than the diameter of the respective opening, theouter radial portion comprising the connecting rods; the airfoil of eachvane having a leading edge and a trailing edge, the pivot section havinga diameter that is smaller than the distance between the leading edgeand the trailing edge; and wherein the radial outer portion, the pivotsection and the airfoil are integrally formed.

The present application also relates to an assembly for an aircraftturbine engine, comprising: an annular row of stator vanes each with anairfoil and a head having a pivot section; an actuator for pivoting thevanes, the actuator comprising a ring and connecting rods connecting thering to each of the vanes; an outer shroud comprising an upstreamsection and a downstream section, both comprising an internal guidingsurface for the gas flow of the turbine engine, and being axially incontact with each other, the upstream and the downstream sectionscomprising, each: an annular row of recesses having a semi-cylindricalshape; and at least one flange positioned between two circumferentiallyadjacent recesses of the annular row of recesses; the recesses of theupstream section being arranged radially and circumferentially incorrespondence with the recesses of the downstream section so as to forman annular row of openings receiving the pivot sections of the vanes,each flange of the at least one flange of the upstream section beingfixed to a flange of the at least one flange of the downstream section,the head of each of the vanes having a radial outer portion on the pivotsection, the outer radial portion extending circumferentially and/oraxially of a length which is greater than the diameter of the respectiveopening; wherein the downstream section comprises a cylindrical surfaceand the ring is provided with pads in radial contact with thecylindrical surface; and wherein each of the flange overlaps radiallythe ring, and each of the flange is axially separated from the ring.

All the features of the embodiments can be combined with all thefeatures of the other embodiments, according to all possible technicalcombinations, unless otherwise not explicitly mentioned.

The present application proposes a specific geometry that allows toassemble the variable orientation vanes without the need to mount eachof the connecting rods once the vane mounted. When the compressorcomprises about fifty vanes per row, the design proposed in the presentapplication results in substantial gain in mounting time. In addition,this design allows the mounting of a one-piece ring (a 360° ring) thatis compact and light.

In the following description, the terms “internal” and “external” referto a positioning relative to the axis of rotation of an axialturbomachine. The axial direction corresponds to the direction along theaxis of rotation of the turbomachine. The radial direction isperpendicular to the axis of rotation. Upstream and downstream are inreference to the direction of the air flow in the turbomachine.

FIG. 1 is a simplified representation of an axial turbomachine. It is inthis case a double-flow turbojet engine. The turbojet engine 2 comprisesa first compression level, called a low-pressure compressor 4, a secondcompression level, called a high-pressure compressor 6, a combustionchamber 8 and one or more levels of turbines 10. In operation, themechanical power transmitted by the turbine 10 via the central shaft tothe rotor 12 sets in motion the two compressors 4 and 6. The lattercomprise several rows of rotor vanes associated with rows of statorvanes. The rotation of the rotor about its axis of rotation 14 thusmakes it possible to generate an air flow and to compress itprogressively until it reaches the combustion chamber 8.

A fan 16 is coupled to the rotor 12 via a gear train 13, and generates aflow of air which splits into a primary stream 18 passing through thevarious aforementioned levels of the turbomachine, and a secondary flow20 passing through an annular duct (partially shown) along the machineto then join the primary flow at the turbine outlet.

The secondary flow can be accelerated so as to generate a thrustreaction for the flight of an aircraft. The primary 18 and secondary 20streams are annular and coaxial flows arranged one into the other.

FIG. 2 is a sectional view of a compressor of an axial turbomachine suchas that of FIG. 1. The flow can be transonic. The compressor may be alow-pressure compressor 4. The rotor 12 comprises several rows of rotorvanes 24, in this case three. It may be a bladed monobloc drum, or itmay include vanes mounted via dovetail attachments.

The low-pressure compressor 4 comprises a plurality of stator vanesrows, in this case four, which each contain a row of stator vanes 26.Some stator vanes may be adjustable in orientation, also called variablestator vanes. The stator vanes rows are associated with the fan 16 orwith a row of rotor vanes to straighten the air flow, so as to convertthe speed of the flow pressure, including static pressure.

A de-icing nozzle 22 can be mounted on a housing that supports a row ofstator inlet vanes 28.

The stator vanes 26 extend essentially radially from an outer shroud 30to an inner shroud 32. The vanes 26 can be attached to the outer shroud30 by means of pins or axles. The shroud 30 defines an inner surface 29which guides the flow of air. According to the present application, theshroud 30 is composed of several axial sections.

The vanes 26 comprise a pivot section 34 in the form of a cylindricalpin which is received in a radial opening of the outer shroud 30. Aconnecting rod 36 integral with the pivot section and pivoting about theaxis of the pivot section 34 makes it possible to maneuver the rotationof the vane. Actuators 40 of the connecting rod 36 are schematicallyshown and will be described later.

FIGS. 3 and 4 illustrate a known example of connection between the headof a vane 26 and the outer shroud 30. The vane 26 comprises an airfoil42 having a leading edge 44 and a trailing edge 46. The head of the vane26 may include a shoulder 48 for centering and positioning the vane 26in the shroud 30 and a groove for receiving a seal. In the knownembodiments, the connecting rod 36 for actuating the pivoting of thevane is fixed by a nut 50 on a threaded portion 52 of the head of thevane. A centering chamfer 54 may be provided at the end of the pivotsection 34.

The head of the vane is received at a location of extra thickness of theshroud 30, which may be in the form of a boss 33.

The connecting rod 36 comprises a conical opening 60 corresponding tothe chamfer 54, a body 62 and a lug 64. As shown in FIG. 4, which is aview from below of the connecting rod 36, the opening 60 may comprise agroove 66 for receiving a pin and thus ensures a common rotation of thevane 26 and the rod 36. The rod 36 also comprises a hole 68 to beconnected to an actuating member (described in FIG. 10). In thisexample, the outer shroud 30 has an opening receiving the pivot section34. The pivot section 34 is inserted into the hole from below (in thedirection of FIG. 3), then the rod 36 is screwed to the thread 52.

FIGS. 5 to 7 show a first embodiment of the connection between the vane26 and the outer shroud 30 according to the present application.

FIG. 5 shows a partial top view of the assembly according to the presentapplication. FIG. 5 references the directions VI and VII whose sectionalviews are illustrated in FIGS. 6 and 7 respectively.

An upstream section 130 and a downstream section 230 form, together, theshroud. Each of the sections comprises a tubular wall 131, 231 definingan inner guide surface 129, 229 and an annular series of recesses 132,232, in the form of half a cylinder, formed in bosses 133, 233. The tworecesses 132; 232 form the opening 31 which receives the head of thevane. The two sections 130, 230 are assembled via screwed elements whichmaintain two flanges 134, 234 adjacent together. The flanges 134, 234may extend from a boss to the circumferentially adjacent boss. FIG. 5shows only one opening.

FIG. 6 is a section in the plane VI: VI defined in FIG. 5.

The shroud comprises two adjacent axial sections 130, 230. Each of thetwo sections comprises a tubular wall 131, 231 and an annular row ofrecesses 132, 232 formed in the bosses 133, 233.

The rod 36 of this first embodiment is welded to the head of the vane.This is done before mounting the vane in the shroud. As the opening 31results from the combination of the two sections 130, 230, the pivotsection 34 can be positioned in a recess 132, 232 of one of the sectionsdespite the size of the rod which is greater than the diameter of theopening 31, then the other section is fixed to embed the pivot section34 in the opening 31.

The rod 36 may have a shape similar to that of FIG. 4, potentiallywithout groove as it becomes unnecessary thanks to the weld.

FIG. 7 shows a view along the plane VII: VII defined in FIG. 5. Thisview shows the assembly of the two flanges 134, 234 by means of a bolt35. Indeed, the flanges 134, 234 have through-holes 135, 235 forassembling the shroud sections to one another by screwed elements 35. Inthe background in FIG. 7 one can see the bosses 133, 233.

FIG. 8 shows another embodiment. As opposed to FIGS. 6 and 7, theconnecting rod 36 is here not welded to the pivot section 34, but thewhole of the vane (airfoil, pivot section, connecting rod) is made inone piece. For example, the connecting rod can be forged or molded withthe rest of the vane. The, functional surfaces (pivot section,extrados/intrados) are then machined. In the same way as for the exampleof FIGS. 6 and 7, it is the two-part design of the openings of theshroud which makes it possible to provide such a one-piece vane with itsconnecting rod.

FIG. 9 represents a partial isometric view of the shroud 30. Inparticular, the one can see some of the bosses 133, 233 as well asflanges 134, 234 and their through-holes (only the holes 235 of thedownstream section 230 are visible). The flanges can completely connecteach of the bosses 133, 233 to the directly neighboring boss. Theupstream section 130 comprises a flange 136 which makes it possible toconnect the shroud to the nozzle of the compressor. The downstreamportion 230 comprises a support surface, preferably a cylindricalsurface 237 for guiding the pads of the synchronizing ring 72 (see FIG.10).

In this example, the flanges 134, 234 rise above the tubular wall 131,231 of a height equivalent to that of the bosses 133, 233.Alternatively, the height of the bosses 133, 233 may be different fromthe height of the flanges 134, 234.

The upstream and downstream sections may have axial centering pins,particularly at the flanges to help centering the position of thesections while they are being assembled. For example, axial pinsprovided in one or more of the flanges 134 can cooperate withcorresponding axial openings in one or more of the flanges 234.

FIG. 10 shows a section of the compressor. The shroud made of the twosections 130, 230 is fixed to the support housing of the de-icing nozzlewhich carries the stator inlet vanes 28 via the upstream flange 136. Adownstream flange 236 is provided on the downstream section.

The actuating mechanism 40 of the pivoting vane comprises a pin 70 whichis received in a distal opening of the rod 36 (equivalent to the opening68 of the rod of FIG. 4). The pin 70 passes through a ring 72 and endswith a pad 74. The pad 74 rests on the cylindrical surface 237 of thedownstream section 230. The cylindrical surface 237 ends upstream by aprojection which limits the movement of the pad 74 axially. Theprojection and the cylindrical surface 237 form a seat for the pad 74.The ring 72 cooperates with as many pins 70 as connecting rods 36. Thering 72 can be pivotally actuated about the axis 14 by appropriate meanssuch as for example a toothed wheel cooperating with a rack provided onthe ring 72. The pivoting of the ring 72 causes a corresponding movementof the pins 70 along the surface 237. This results in the rotation ofthe rod 36 and of the vane 26 around the axis 38.

The ring 72 is also called synchronizing ring, operating ring, actuatingring or control ring.

The general shape of the downstream section 230 allows the mounting ofthe ring 72 and pins 70. In the example illustrated in FIG. 10, theflange 236 has an outer diameter which is substantially smaller than theinner diameter of the ring 72, thus allowing the pins 70 with their pads74 to be inserted into the ring 72 before the assembly (ring 72, pins 70and pads 74) is slid axially upstream to be mounted on the downstreamsection 230.

For the assembly of the sections, the following steps are followed: thepivot sections 34 of the vanes are inserted into the recesses 232, thenthe upstream section is brought to enclose the pivot sections 34 in theopenings 31 thus formed. The flanges 134, 234 are then fixed to eachother. Then the actuating pins 70 carried by the synchronizing ring 72can be assembled to the connecting rods 36. Alternatively, the fixing ofthe pins 70 to the rods 36 can take place before the upstream section130 is positioned in contact with the downstream section 230. Also, thering 72 can be inserted around the downstream section 230 before thevanes 26 are brought into the recesses 232.

The embodiment described here has two sections 130 and 230 but one ormore additional sections may be provided and assembled in the same way,each of the sections having an annular row of recesses facing therecesses of the adjacent section to form openings receiving vane headswhich may or may not be of variable orientation.

I claim:
 1. An assembly for an aircraft turbine engine, comprising: anannular row of stator vanes each with an airfoil and a head having apivot section; an actuator for pivoting the vanes, the actuatorcomprising: a ring and connecting rods connecting the ring to each ofthe vanes; an outer shroud comprising an upstream section and adownstream section, both comprising an internal guiding surface for thegas flow of the turbine engine, and being axially in contact with eachother, the upstream and the downstream sections comprising, each: anannular row of recesses having a semi-cylindrical shape; and at leastone flange positioned between two circumferentially adjacent recesses ofthe annular row of recesses; the recesses of the upstream section beingarranged radially and circumferentially in correspondence with therecesses of the downstream section so as to form an annular row ofopenings receiving the pivot sections of the vanes; each flange of theat least one flange of the upstream section being fixed to a flange ofthe at least one flange of the downstream section; the head of each ofthe vanes having a radial outer portion on the pivot section, the outerradial portion extending circumferentially and/or axially of a lengthwhich is greater than the diameter of the respective opening; theupstream and downstream sections being provided with an annular row ofradial thickened portions or bosses within which the recesses areformed; and the radial thickened portions or bosses being an annular rowbeing interconnected to each other by the flanges.
 2. The assemblyaccording to claim 1, wherein the downstream section comprises: a seatfor receiving the actuator, the seat comprising: a cylindrical surface.3. The assembly according to claim 2, wherein the cylindrical surfacedefines a diameter and downstream of the seat, the downstream sectiondoes not extend radially of more than said diameter.
 4. The assemblyaccording to claim 1, wherein a flange of the at least one flange isarranged between two circumferentially neighboring recesses of therespective annular row of recesses of the upstream and the downstreamsection.
 5. The assembly according to claim 4, wherein the flangeextends circumferentially completely from one recess to the neighboringrecess of the two circumferentially neighboring recesses.
 6. Theassembly according to claim 1, wherein each of the at least one flangecomprises two through-holes for receiving screws, each flange having acircumferential length between two neighboring recesses and thethrough-holes being at a distance from one of the two neighboringrecesses that is less than a quarter of the circumferential length ofthe flange.
 7. The assembly according to claim 1, wherein the bosseshave an external truncated surface.
 8. The assembly according to claim1, wherein the upstream section comprises a fixation flange at its axialupstream end for assembling the upstream section to a fan casing or ade-icing nozzle.
 9. The assembly according to claim 1, furthercomprising a third section with semi-cylindrical recesses, the thirdsection being connected to the downstream section and the recesses ofthe third section forming openings with additional semi-cylindricalrecesses provided at the downstream end of the downstream section. 10.An assembly for an aircraft turbine engine, comprising: an annular rowof stator vanes each with an airfoil and a head having a pivot section;an actuator for pivoting the vanes, the actuator comprising a ring andbeing connected to each vanes through connecting rods; an outer shroudcomprising an upstream section and a downstream section, both comprisingan internal guiding surface for the gas flow of the turbine engine, andbeing axially in contact with each other, the upstream and thedownstream sections comprising, each: an annular row of recesses havinga semi-cylindrical shape; and at least one flange positioned between twocircumferentially adjacent recesses of the annular row of recesses; therecesses of the upstream section being arranged radially andcircumferentially in correspondence with the recesses of the downstreamsection so as to form an annular row of openings receiving the pivotsections of the vanes; each flange of the at least one flange of theupstream section being fixed to a flange of the at least one flange ofthe downstream section; the head of each of the vanes having a radialouter portion on the pivot section, the outer radial portion extendingcircumferentially and/or axially of a length which is greater than thediameter of the respective opening, the outer radial portion comprisingthe connecting rods; and the airfoil of each vane having a leading edgeand a trailing edge, the pivot section having a diameter that is smallerthan the distance between the leading edge and the trailing edge; andwherein the radial outer portion, the pivot section and the airfoil areintegrally formed.
 11. An assembly for an aircraft turbine engine,comprising: an annular row of stator vanes each with an airfoil and ahead having a pivot section; an actuator for pivoting the vanes, theactuator comprising a ring and connecting rods connecting the ring toeach of the vanes; an outer shroud comprising an upstream section and adownstream section, both comprising an internal guiding surface for thegas flow of the turbine engine, and being axially in contact with eachother, the upstream and the downstream sections comprising, each: anannular row of recesses having a semi-cylindrical shape; and at leastone flange positioned between two circumferentially adjacent recesses ofthe annular row of recesses; the recesses of the upstream section beingarranged radially and circumferentially in correspondence with therecesses of the downstream section so as to form an annular row ofopenings receiving the pivot sections of the vanes; each flange of theat least one flange of the upstream section being fixed to a flange ofthe at least one flange of the downstream section; the head of each ofthe vanes having a radial outer portion on the pivot section, the outerradial portion extending circumferentially and/or axially of a lengthwhich is greater than the diameter of the respective opening; whereinthe downstream section comprises a cylindrical surface and the ring isprovided with pads in radial contact with the cylindrical surface; andwherein each of the flange overlaps radially the ring, and, each of theflange is axially separated from the ring.